If man was making said changes at the rate random useful mutations tend to occur in nature I don't think anyone would be concerned. And we typically do more tha

If man was making said changes at the rate random useful mutations tend to occur in nature I don't think anyone would be concerned. And we typically do more than just tweak a genetic component in a single individual and see how it fares against existing populations - if the change suits our short term goals, we'll do everything we can to ensure that becomes the dominant variant, often destroying the genetic diversity that provides long term durability in the process.